Pressure casting apparatus.



R. N. LE GRON. PRESSURE CASTING APPARATUS.

APPLICATION rum) APR. 20, 1908.

927,661. Patented July 13, 1909.

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ROBERT N. LE GRON, OF ST. LOUIS,.MISSOURI.

PRESSURE CASTING APPARATUS.

Specification of Letters Patent.

Patented July 13, 1909.

Application filed April 20, 19b8, Serial No. 428,175.

To all whom it may concern:

Be it known that I, ROBERT N. LE CRoN, a citizen of the United States, residing at St. Louis, in the State of Missouri, have invented certain new and useful Improvements in Pressure Casting Apparatus; and I do hereby declare the following to be a full, clear, and exact description of the same, reference being had to the accompanying drawings, forming a part of this specification, and to the figures and letters of reference marked thereon.

This invention relates to improvements in apparatus for facilitating the making of small and delicate castings with the aid of pneumatic or gas pressure for forcing the molten metal into the interstices of the mold.

The apparatus forming the subject-matter of the present application is particularly designed for use by dentists in the making of inlay castings or cast metal dental appliances of any character, although it is well adapted for use by jewelers, and others, for the production or reproduction of articles of jewelry for personal 'wear or adornment.

The objects of the invention are to provide a simple, inexpensive apparatus not liable to get out of order or be broken in use.

A further object of the invention is to provide an apparatus which shall be as nearly as possible automatic in the application of the pressure to the molten metal, and which requires no complicated accessories for. its operation.

A further object of the invention is to provide an apparatus with which flasks or cups for molds of various sizes may be employed, thereby enabling the user to make small and delicate castings without the necessity of employin a flask of large dimensions, thereby efiecting a saving in investment material, and other expenses incident to the employment of flasks of larger dimensions than necessary for the particular object be ing cast.

Further objects of the invention are to provide a receiver or casting chamber adapted to be closed or made air-tight without the employment of packings and to provide for the admission of air or gas pressure to the receiver without danger of chilling the molten metal.

The invention consists in certain novel details of construction and combinations and arrangements of parts all as will be now described and particularly pointed out in the appended claims.

Referring to the accompanying draw ings: Figure 1 is a perspective view of an apparatus embodying the present improvements, portions being broken away, and the pressure "supply tank shown diagrammatically. Fig. 2 is a vertical section taken in a plane from front to rear of the casting apparatus proper. Fig. 3 is a sectional view of flasks to illustrate the fact that flasks of various dimensions may be employed in the same apparatus. Fig. 4 is a sectional View showing an inverted cup containing a material, the use of which will be hereinafter explained.

Like characters of reference in the several figures indicate the same parts.

The casting apparatus proper embodies a receiver which is of proper dimensions to contain a flask of the largest dimensions capable of use with the apparatus, and, as

shown, this receiver is formed by a bot-tom section A and a top section B, one of said sections being movable toward and from the other to close and open the receiver, the meeting edges being preferably mitered or made to telescope, one within the other, as at a, b, in order to form a receiver which is substantially closed against the escape-of internal pressure before the two sections have completed their closing movement. In the preferred construction, the lower section A is provided with an extended base A adapted to be mounted on a table of other suitable support, and extending upwardly from this base A are guide rods C, upon which the upper section B is mounted and guided in its movement. As a convenient and thoroughly mechanical construction, the guides C may be connected by a bridge-piece G in which a central stem B projecting upwardly from the upper section B takes its hearing. The stem 13 is conveniently provided with a handle B at the upper end, whereby the upper section B of the receiver may be moved by the operator into either its open or closed position, although in the preferred construction, and as shown, the upper section B is provided with downwardly extending rod and chain connections such as indicated at D, D adapted to support a cross piece forming a foot or treadle connection D whereby the upper section may be drawn down with any necessary or desired pressure, and without undue exertion on' the part of the operator. The upper or movable section is adapted to be held in its closed position and where desired in its open position by a spring-pressed catch E, preferably pivotally mounted on the bridge-piece C and adapted to enter one or the other of the notches -e in the stern B of the movable seC tlon.

ceiver through a supply duct G, Fig. 2, to which the pressure may be conducted through a flexible tube H, from a pressure supply tank H or other suitable source, and the admission of the pressure to the receiver is controlled by a valve adapted to be opened by the closing movement of the receiver after thereceiver has been sufficiently closed to prevent the escape of internal pressure, between the meeting edges of the sections. 1

lhe valve for controlling the pressure supply, lettered I in the accompanying drawings, is conveniently located in a valve casing K, forming a part of the pressure supply duct and mounted directly upon the upper or movable section B of the receiver. An operating or opening stem 71 for the valve extends downwardly below the valve casing in position to contact with an adjustable stop L, mounted on or forming a part of the lower section A, the arrangement being such that the stop may be adjusted to open the valve only after the two sections have commenced to telescope togetherand the final opening of the valve will be eflected when the closing movement of the receiver is completed.

The bottom of the lower section is provided with a central vent A and the inner face of said bottom is preferably made substantially fiat and smooth, while the cups or flasks M are provided with downwardly extending peripheral flanges m adapted to seat on said bottom around the vent A and to form with said bottom a. substantial seal against the escape of pressure beneath the flange. The bottom of the flasks is perforated and elevated slightly above the edges of the flanges, thereby providing an air chamber within said flanges, and as a consequence when the receiver is closed and pressure admitted thereto above and around the flask, the only escape for said pressure is through the flask itself. By having the bottom of the flask uniformly perforated the pressure is equally distributed and, as will I hereinafter appear, each part of a mold may be effectually relieved from its contained air by the escape of thelatter through the interstices of the investingmaterial, without danger of forming channels of suflicient size to permit the entry of molten metal.

In using the apparatus, the flask is prepared usually by surroundlng the wax pat- Air or gas pressure is admittedto the retern with investing material and embedding the said pattern in such material within the flask, a suitable depression or cavity being formed in the upper surface of the investing material in which the metal may be melted by means of a blow-pipe, electric are, or usual appliances employed for this purpose.

,The wax pattern having been removed, preferably by inverting the flask and heating the same, the flask is placed in the lower section of the receiver and the metal placed in the depression in the top of the flask and melted. As soon as the metal is suiliciently molten the receiver is closed and the pressure simultaneously admitted, thereby forcing the molten metal into the mold, and .at the same time forcing the. air which may have occupied the area of the mold to a greater or less extent out through "the investing material, perforated bottom of the flask, and vent A In order to make the use of the apparatus possible where no auxiliary pressure supply is available, the adjustable stop L may be moved, so that the valve will not be opened, or the pressure supply duct may be plugged in any suitable way, and to create a pressure when the receiver is closed, steam may be generated by the heat of the flask and adjacent parts from the water contained in a pad of asbestos or other material located in the upper movable section B. For instance, the inverted cup or box N, Fig. l, may be located in the upper section B and contain either an absorbent pad of asbestos or a plastic molding material, indicated at N If the material employed is a plastic mass, the cup N should be of such dimensions as to pass down around the upper edge of the flask, thereby bringing the plastic mass into contact with the upper surface of the investing material and flask. As the result of this operation, the air trapped in the cavity in the flask, or the plastic material itself comforce the latter down into the mold, the oper- 11o blow holes orfins of any character, save the usual sprues formed by. the entrance openings for the metal.

It Wlll be noted that the sections of the receiver are closed substantially air tight without the use of packings of any descrip- 126 tion, thereby eliminating the danger of rendering the apparatus inoperative by burning or dryingout of the packings. The only escape for the air is through the. special investing material, and the flasks do not have to be carefully centered or fitted into place so long as the central vent is under the perforated bottom and with apparatus of ordinary slze the flasks are all ofsuch size that even when in contact with the side of 130 the receiver the vent will be within the annuversely or at the scle. thus avoiding danger a of chilling the mofen metal.

Having thus des ribed the invention, what is claimed, is:

1. In a pressure casting apparatus, the

combination with the receiver for the llask 5 formed in separable sections movable one toward and from the other and the lower sectionbeing provided with a bottom vent, of a llask having a perforated bottom and a pcripheral flange around the perforated bottom adapted to seat in the lower section around the said vent, whereby air and gases mav be forced from the receiver through the toward and from the other, and the lower ward] y extending connections for depressing the upper section, and a catch for holding the upper section down.

t'. tn a pressure casting apparatus, the combination with the receiver for the flask embodying the bottom section having an extended base and vented bottom and the vertical guides supported by said section, of the inverted cup-shaped top section mounted on the vertical guides and movable toward and from the bottom section, a downwardly extending foot operated connection for deplessing the upper section, and a spring pre sed catch for holding the upper section against movement.

7. In a pressure casting apparatus, the combination with the receiver for the flask embodying upper and lower sections movable one to Md and from the other to close and open the receiver, the lower section being provided with a vented bottom, of an air duct for supplying pressure to the receiver, a valve in said duct opened by the movement of the sections to close the re- 2. In a pressure casting apparatiiis. the; combination with the receiver for the llask 1 formed in separable sections movable onei section being provided with a plane internal 1 face having a vent therein, of a tlask having a perforated bottom and a downwardly ex- 3 tending peripheral flange adapted to seat on the plane face of the receiver around the vent.

3. In a pressure casting apparatus, the combination with the receiver for the Mask formed in separable upper and lower sec- 5 tions, of rods mounted on the lower section and forn'iing the guide ways for the upper section and a catch for holding the sections closed.

4. In a pressure casting apparatus, the combination with the receiver for the flask formed in separable upper and lower sections, the lower section being provided with a vented bottom having a plane inner face,

of guide rods for the upper section mounted t on the lower ection. a catch tor holding the sections clo ed. and a llaslt having a perforated bottom and peripheral flange mating around the said vent.

combination with the receiver for the iiaslt formed in separable upper and lower sections, the lower section being provided with a vented bottom, of guide rods for the upper section supported by the lower section, downeeiver. and a. flask having a perforated bottom adapted to seat over said vent, whereby air and gases in the flask may escape through the perforated bottom and vent.

h. in a pressure casting apparatus, the combination with the receiver for the flask embodying upper and lower sections movable cue toward and from the other to close and open the receiver and the lower at cuon being provided with a vented bottmn, of an air duct for supplying pressure to the receiver and a control valve for said duct mounted on one section and having a stem projecting in position to contact with the other section to open the valve as the receiver is closed.

3). In a pressure casting apparatus, the

combination with the receiver tor the flask embodying upper and lower sections movable one toward and from the other to close and open the receiver and the lower section beingprovided with a vented bottom, of a pressure inlet. duct carried by the upper scetiom and a 'alve controlling said duct 5 ing a downwardly extending ope 'ating stem adapted to contact with the lower seetion to open the valve as the sections come in a pressure casting apparatus, the

together.

It. LE URON.

d 'itnesses:

HENRY B. Smear, DANIEL J. BYRNE. 

